Determine the interest on the following notes: $($Use $360$ days for calculation.$)$

$($a$)$

$$5,800$ at $6\%$ for $90$ days.

$

$($b$)$

$$800$ at $9\%$ for $5$ months.

$

$($c$)$

$$7,200$ at $7\%$ for $60$ days.

$($d$)$

$$1,800$ at $7\%$ for $6$ months.

$